Combination isoparaffin-olefin and aromatic-olefin alkylation process



\ H. H. LEE COMBINATION ISOPARAPFIN-OLEFIN AND AROMATIC-OLEFIN ALKYLATION PROCESS- Filed Deo. 19, 1947 Jan. s, 1952 y Patented Jan. 8, 19.52

COMBIATIOIN ISOPARAFFIN-OLEFIN AND l AROMATIC-OLEFIN ALKYLATION PROCESS Henry H. .Lee, Bartlesville, Okla., assignor to Phillips Petroleum Company, a. corporation of Delaware Application December 19, 1947, seria1Ne.792,699`

' o 7 Claims. (Cl. 26o-671) This invention "relates to the alkylation of hydrocarbons. In one embodiment it relates to a unitary process for alkylation of paraflnic and aromatic hydrocarbons catalytically. In one specic embodiment this invention relates to an improved method for the separation of emulsilied reactor eluents from a paraiiin alkylation unit and an aromatic alkylation unit.

It is well known that paraiilnic hydrocarbons, particularly isoparaliins, and aromatic hydrocarbons can be alkylated with olenic hydrocarbons in the presence of alkylation catalyst, such as anhydrous hydrouoric acid. sulfuric acid, aluminum chloride or the like to produce higherboiling hydrocarbons.

In uid catalytic alkylation processes, including both paraflinic and aromatic alkylation, the reactor eluent which is in the form of a hydrocarbon-catalyst emulsion, is passed to a settling tank where it separates into a catalyst phase and a hydrocarbon phase. The hydrocarbon phase which comprises reaction products, unreacted reactants, and usually some dissolved or entrained catalyst is passed to separation equipment for the recovery of desired products and subsequent recycling of' unreacted reactant hydrocarbons. The catalystphase contains in addition to the catalyst, catalyst soluble oils, unreacted reactant hydrocarbons, and minor amounts of light hydrocarbons, such as ethane and propane. All, or

a part of the catalyst phase is recycled to the alkylation reactor while a portion may be withdrawn from the system for subsequent purication and return to the system.

I have found that the rate of separation of the reactor eliluent hydrocarbon-catalyst emulsion of an aromatic alkylation unit into a hydrocarbon phase and a catalyst phase is slower than the rateof vseparation of reactor eilluent into a hydrocarbon 'phasefand a catalyst phase in a parafiin'alkylationA unit. Furthermore, the degree of such separation in aromatic alkylation is not as eiilcient as is desired resulting in the loss of appreciable quantities of reactant hydrocarbons in 4the catalyst phase.

` I have discovered that when the emulsiled reactor-eilluents from a catalytic parain alkylation unit and from a catalytic aromatic alkylation lunit respectively wherein the alkylation catalyst employed is selected from the group consisting of 'hydrogen fluoride, sulfuric acid and aluminum chloride are combined and the resulting mixture passedto common settling and separation systems, certainV economic and operational advantages 4arev obtained." By` combining- '2 the emulsifled eluents from thevparaiiin and aromatic alkylation reactors and passing the resulting mixture to a common settler, faster and cleaner separation of the eiiluent into a hydrocarbon phase and a catalyst phase is obtained than is obtained where the aromatic alkylation eiiiuent is allowed to separate alone. This is due, chiefly to the fact that the density of the hydrocarbon phase from the aromatic alkylation unit is lowered by dilution with the paraffin hydrocarbons. In some cases, aromatic hydrocarbons and products of aromatic alkylation have about the same density as the alkylation catalysts, such as anhydrous hydrogen fluoride. Therefore, the mixing of the reactor eluents from paraffin and aromatic alkylation units tends to decrease the density of the reactor eluent from the aromatic alkylation unit resulting in faster and cleaner phase separation. Also, the lighter paraiin hydrocarbons contained in the paraffin alkylation reactor eiiiuent such as isobutane, exhibit a solvent action on the unreacted aromatic hydrocarbon thereby tending to prevent them from being dissolved in the catalyst phase, particularly when hydrogen iluoride is' used' as a catalyst. Aromatic hydrocarbons, such as benzene, are quite soluble in hydrogen fluoride. In addition, a common catalyst recovery system can be Vemployed, resulting in a saving in labor, investment and operating expense. l

An object of this invention is to provide an improved process for the alkylation of hydrocarbons.

Another object is to provide an improved method for separating the reactor eiiluents from a catalytic paraiiin alkylation unit and a catalytic aromatic alkylation unit.

` Still another object is to provide a method whereby the total time for the separation of reactor eiiiuents from a' catalytic parain alkylation unit and a catalytic aromatic alkylation unit into a catalyst phase and a hydrocarbon phase is reduced.

Another object of my invention is to reduce 'aromatic hydrocarbon loss due to carry over in` catalyst phase.

Other objects and advantages of this invention will be apparent to those skilled in the art from the accompanying disclosure and discussion.

The accompanying drawing is a diagrammatic illustration of an arrangement of apparatus suitable for conducting the process of the present invention. VThough I illustrate the processbof my invention by using =specic feed stocks, such as 5 and are well-known inthe art.' The-specific:tem perature, pressure,l contact time', etc., used in each of these alkylationunits will depend upon the specic reactants employed. The exact conditions can easily be determined by mere routine test in each case. In general, however, the alkylation of. isoparaflins and aromatics with olefins in the presence of alkylation catalysts, such as hydrogen fluoride, is effected at temperatures in the range of from'about 0 F. to about 200 F.,

The pressure in the alkyiation zone is ordinarily maintained suiciently high to insure liquid phase operation. The time relationship may be explained by means of the so-called space time, which is deiined as the volume of catalyst within the reaction zone divided by the volume rate per minute of hydrocarbon reactants charged to the zone. Usually the space time will fall within the range of from about 5 to about 80 minutes, although in certain cases it may be desirable' to extend this range in either direction. As is wellknown inthe alkylation art, an excess of alkylatable paraiiin and aromatic hydrocarbons over olens should be maintained in the alkylation zone at all times, e. g. a mol ratio of alkylatable paraihns to olens and of aromatics to oleflns from about 3:1 or 4:1 to about 10:1 or even higher. The reaction mixture effluent from the alkylation zone is passed to an acid settling system where it separates by gravity into a hydrocarbon phase and an acid phase. The time necessary for this settling will vary considerably, depending uponv the particular hydrocarbons present, but usually from about 10 to 60 minutes is sufficient for this settling time. According to the process of my invention the total time necessary for the separation of the mixture of the effluents from the parafiin alkylation zone and the aromatic alkylation zone is less than the sum total of time required for separation if the effluent from each of the reaction units was all 6 usually it'fispreferable to use -a'temperature in the range bf about' 270 to 280fF: A 'preferred pressure of Vabout l25 tor'50 pounds "per square vinch absolute is maintained on the bottom of the fractionator; however, ii. a higher. temperature is used than thatV indicated, a .correspondingly higher pressure may be employed. The temperature at the top of the fractionating column may be in the range of about 85 to 150 F., but usually about'v 95 to about. 110 F. is preferable. A pressure in the range of about 20 to about 40 pounds-per square inch absolute in the top' ofthe column is usuallysufcient for this temperature.

ing of the density of the hydrocarbon phase from v the aromatic alkylation zone. The recovery of the so-called spent-acid catalyst, such as spent hydroiiuoric acid is conducted in a suitable catalyst recovery system. The recovery of catalyst such as hydrogen fluoride and H2804 is well known in the art. In case of the recovery of hydrogen fluoride in a fractionating system, a temperature in the range of about 250 to about 300 F. or higher is used, depending upon the specific characteristics of the used catalyst material being treated. The temperature at the bottom of the fractionating zone may be maintained at between about 260 and 300 F., but

It is to beunderstood that this 'invention' should Y nctibe necessarily limited to theabove discussion and description, and thatmodiiicjations and variations may; be made without departing from the invention and-fromthe scope of the claims. 1 Iclam: 511;.. i.. L' `l. In a process wherein the concomitant catalytic. alkylation of .an alkylatable parafllnichydrocarbon .with an olen, land an aromatic hydrocarbon with aniolen having at least three and not more than 'sixteen'carbon atoms per molecule is 'carried utfin a separateiirst and a separate second alkylation'zon, respectively, and wherein said second alkylation zone is free of the alkylation product of said first vzone and wherein the alkylation cata1yst enacted 'from the group consisting of hydrogeniiuoride, sulfuric acid and aluminum chloride, the improvement which comprises;l combining the 'emulsied rreaction eiiiuet from said rst alkylation zone directly with the emulsied reaction eiiiuent from said `second alkylation zone; separating the resulting admixture into a catalyst phase and a hydrocarbon phase in a catalyst settling zone; returning a portion of said catalyst phase to said second alkylation zone and returning a portion of said catalyst phase to said rst alkylation zone passing a portion of said catalyst phase to a catalyst recovery zone; returning a portion of said recovered catalyst to said first alkylation zone and a portion to said second alkylation zone.

2. In the process according to claim 1 wherein the catalyst used is hydrogen fluoride.

3. The process according to claim 1 wherein at least six and not more than twelve carbon atoms per molecule is carried out in a separate rst and a separate second alkylation zone, respectively, and wherein said second alkylation zone is free of the alkylation product of said rst zone, the improvement which comprises; combining the emulsied reaction eluent from said rst alkylation zone directly with the emulsied reaction mixture eiiuent from said second alkylation zone; separating the resulting admixture into an acid phase and a hydrocarbon phase in an acid settling zone; returning a portion of said acid phase to said second alkylation zone; passing a portion of said acid phase to an acid recovery zone; removing hydrogen uoride from said acid phase and returning a portion of said hydrogen fluoride to said first alkylation zone.

6. In a process wherein the concomitant hydrogen uoride catalytic alkylation of isobutane with butene and benzene with an olen having at least six and not more than twelve carbon atoms the emulsified'reaction emnent from said first` alkylation zone directlywith the emulsied ree Y action euent from said second alkylation zone; separating 'the resulting admistureinto an acid phase and a hydrocarbon yphase in an acid set tling zone: returning` a` portion ot said acid phase to :said seconlalkylation Vzone and returning .a

pcrtionofsaid acid phase yto said first aikylationl zone:- passing a portion ofV said acid phase to.y an acid recovery zone: removing hydrogen fluoride from said .acid phase said acid recovery `zone and returning a portion ci said hydrogen nuoride to said first elkylation .zone and a portion to .said second alkylation zone.` 1

i7. In'axprocess wherein the concomitant .hydrogen nuoride catalytic alkylation of isobutane with butene, and benzene with an olefin having atleast six andv not more than twelve-carbon atoms perrinolecule is carriedout a, separate first and a separate second alkylation zone,l respectively. andwherein Said second .alkylation zone free of the alkylated product 0f said iirst zone. the improvement which, comprises: comhining the emulsiiied reaction` eiuent from. said first alkylationl zone directly withv the emnlsied reaction` eiiiuent from said second` alkyiation zone; Separating the resulting` admitnre into an acid' phase ,andv a hydrocarbon phase in an acid settling zone; returning a. portion of said acid phase rtn :said second alkylation zone; returning a portion: of said acid phase. to said first alkyla tion zone; removing from said hydrocarbon phase .a hydrocarbon fraction comprising benzeneand'hexane; contacting said benzene-hex ane fraction with a Vselected solvent for said benzene in a separating zone whereby a portion oi said :benzene is dissolved in said solvent; separating said dissolved benzene from said solvent in a distillation zone; returningsaidbenzene from said .distillation zone to said second alkyla.- tion, zoneffand returning said solvent to said benzene-hexane .separating cone.

EEEERENCES CITED The following references are of record in the ie'of this patent: UNITED STATES PA'IEN'ISl 

1. IN A PROCESS WHEREIN THE CONCOMITANT CATALYTIC ALKYLATION OF AN ALKYLATABLE PARAFFINIC HYDROCARBON WITH AN OLEFIN, AND AN AROMATIC HYDROCARBON WITH AN OLEFIN HAVING AT LEAST THREE AND NOT MORE THAN SIXTEEN CARBON ATOMS PER MOLECULE IS CARRIED OUT IN A SEPARATE FIRST AND A SEPARATE SECOND ALKYLATION ZONE, RESPECTIVELY, AND WHEREIN SAID SECOND ALKYLATION ZONE IS FREE OF THE ALKYLATION PRODUCT OF SAID FIRST ZONE AND WHEREIN ALKYLATION CATALYST IS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN FLUORIDE, SULFURIC ACID AND ALUMINUM CHLORIDE, THE IMPROVEMENT WHICH COMPRISES; COMBINING THE EMULSIFIED REACTION EFFLUENT FROM SAID FIRST ALKYLATION ZONE DIRECTLY WITH THE EMULSIFED REACTION EFFLUENT FROM SAID SECOND ALKYLATION ZONE; SEPARATING THE RESULTING ADMIXTURE INTO A CATALYST PHASE AND A HYDROCARBON PHASE IN A CATALYST SETTLING ZONE; RETURNING A PORTION OF SAID CATALYST PHASE TO SAID SECOND ALKYLATING ZONE AND RETURNING A PORTION OF SAID CATALYST PHASE TO SAID FIRST ALKYLATION ZONE; PASSING A PORTION OF SAID CATALYST PHASE TO A CATALYST RECOVERY ZONE; RETURNING A PORTION OF SAID RECOVERED CATALYST TO SAID FIRST ALKYLATION ZONE AND A PORTION TO SAID SECOND ALKYLATION ZONE. 